Field of the Invention
The invention concerns a navigation device and a method for position determination by means of dead reckoning, in particular for motor vehicles, in which measured values for distances traveled and directions are summed. A position calculated in this way is compared with a probable position on a digitized road map and corrected. The process is called map matching.
German published patent application DE 35 19 277 A1 discloses a navigation method for vehicles which is based on dead reckoning. On reaching a final destination the user can determine the difference between the calculated position and the actual location by pressing a button. This is used to determine correction values for the measurement of the direction and for the measurement of the distance traveled. These correction values can be used to correct inherent, constant errors in the measurement of direction and distance.
International patent application WO 93/09509 discloses a sensor system for vehicle navigation in which an error component of a sensor is determined in order to recalibrate the sensor.
U.S. Pat. No. 5,394,333 describes a hybrid vehicle navigation system with GPS and dead reckoning. A position calculated using dead reckoning is drawn on a road map. The difference between the position on the road map and a position found using GPS is used to determine a correction value for the GPS navigation system.
From German published patent application DE 42 11 933 A1 there is known a navigation device for dead reckoning which produces correction values for a GPS receiver. A correction value is derived by comparing a position calculated by dead reckoning with a road position coordinate read from a mass memory device. This correction value is fed to the GPS receiver in order to adjust the position data acquired via satellite reception. Digitalization errors in the roads stored in mass memory are integrated unfiltered in the correction value.
From German published patent application DE 35 19 277 there is known a navigation method for vehicles with a dead reckoning device in which on reaching a destination a correction value is derived through determination of the difference between the destination entered and the location calculated by dead reckoning.